At the turn of 2025, an unfortunate technical issue with the production of ERA5 resulted in a large part of satellite observations not being used. This led to small but systematic differences, impacting mainly humidity in the tropics, and in lesser extent other ERA5 parameters as well from the 1st of January 2025 onwards.
By the time the issue was discovered however, some ERA5T data from 1st of January 2025 had already been published in the Climate Data Store.
This means that the following ERA5T data sets have been affected from 1st January 2025 onwards:
ERA5T and ERA5-Land-T hourly data:
- ERA5 hourly data on single levels from 1940 to present
- ERA5 hourly data on pressure levels from 1940 to present
- Complete ERA5 global atmospheric reanalysis
- ERA5-Land hourly data from 1950 to present
ERA5T daily data:
- ERA5 post-processed daily statistics on single levels from 1940 to present
- ERA5 post-processed daily statistics on pressure levels from 1940 to present
- ERA5-Land post-processed daily statistics from 1950 to present
ERA5 and ERA5-Land monthly data is not affected.
Other ERA5 related data:
- Thermal comfort indices derived from ERA5 reanalysis (ERA5-HEAT)
- Agrometeorological indicators from 1979 to present derived from reanalysis (AgERA5)
A solution is being implemented and the currently affected data will be corrected in the final version that will be made available in about 2-3 months time.
However, in contrast to what we have done in the past (e.g. in October 2024) it was decided that ERA5T will also be corrected as we will overwrite the published ERA5T with the corrected version. So for ERA5 and ERA5-Land hourly data users will not need to wait for 3 months to pick up the corrected data.
That process has now started and we expect it to complete by early next week. From that moment onwards, (re-)downloading ERA5T and ERA5-Land-T will contain the corrected datasets from the beginning of 2025. Please watch this topic to be kept informed.
Please note that the Climate Pulse application is also affected by this issue.
We are sorry for the inconvenience this may cause. Thank you for your patience.
ECMWF Support
on behalf of the Reanalysis team at ECMWF